This invention relates to an ignition system having capacitive intermediate storage of the energy required for the ignition pulse. The present invention relates, more particularly, to an ignition system having a plurality of storage capacitors which are charged from a battery via a charging device, the capacitors being temporarily discharged sequentially by means of switches via an ignition transformer so as to provide an input to a spark plug. The ignition system is particularly suitable for use in conjunction with Otto and Wankel engines.
Capacitor ignition systems are known per se and are described in detail, particularly in comparison to previously generally employed coil ignition systems; see, for comparison, Motortechnische Zeitschrift, Vol. 24, pages 291-295 and pages 439-443 (1963) as well as Elektronik, Vol. 8, pages 235-238 (1966).
A comparison of the high voltage capacitor ignition systems (HVCI) and the coil ignition systems shows that the capacitor ignition systems are substantially insensitive to soiling of the spark electrodes of the spark plug and its adjacent portions which results during operation from lead, soot and combustion residues. The spark duration during discharging at the spark electrodes of the spark plug for capacitor ignition is ordinarily very short compared to the spark duration conditions for coil ignition. Whenever coil ignition is used, a series of subsequent sparks and glow periods follow the actual initial spark ignition at the spark plug, occuring at the end of the voltage rise time, when voltage across the plug is in its maximum. In such a case, even if the spark ignition occuring at the voltage peak itself were not able to cause a fuel ignition, the prepared fuel-air mixture can nevertheless be ignited by the subsequent sparks (required spark duration up to about 1400 .mu.sec.) The known ignition with HVCI involves substantially only the initial spark and a relatively very short follow-up discharge time (about 50 .mu.sec.). Depending on the type of engine and its operating state, individual fuel mixture ignitions may be missing because the single occurring spark between the electrodes of a spark plug will not always initiate the fuel ignition with certainty; for example, whenever the composition of the fuel-air mixture is unfavorable and/or the constituents are inhomogeneously mixed.